The White House said Monday that the Justice Department’s firing of 46 U.S. attorneys was standard practice for a new administration, while speculation grew that former Manhattan federal prosecutor Preet Bharara turned his firing into a cause celebre as a potential springboard to higher office.

Responding to media outrage over the firings, the White House said Monday that President Trump was merely engaging in the same kind of clearing out of political appointees that presidents before him have done.

“This is a standard operating procedure for a new administration around this time,” said White House press secretary Sean Spicer. “This is a standard action that takes place in most administrations.”

For example, President Bill Clinton fired 93 U.S. attorneys soon after taking office in 1993 — among them Jeff Sessions, now attorney general, who at the time was U.S. Attorney for the Southern District of Alabama. Presidents George W. Bush and Barack Obama engaged in similar efforts to replace federal prosecutors with their own appointees.

But when Mr. Sessions notified the 46 holdover prosecutors from the Obama administration on Friday to resign, there was a furor in much of the mainstream media, accusing the administration of being unfair.

Media reports especially singled out Mr. Bharara, the U.S. attorney for the Southern District of New York and a former aide to Senate Minority Leader Charles E. Schumer, New York Democrat, as a victim of political motivation.

Mr. Bharara seemed to encourage that notion by asserting on Twitter that he forced the administration to fire him rather than resign. He said Mr. Trump had promised him during the transition that he wanted Mr. Bharara to stay on.

Expectations are high that Mr. Bharara, 48, will run for office, possibly mayor of New York City this year or governor of New York in 2018. As soon as he announced his firing via Twitter on Saturday, New York City Public Advocate Tish James responded, “Run, Preet, Run.”

Hans von Spakovsky, a former Justice official in the George W. Bush administration and a legal analyst at The Heritage Foundation, said he believes Mr. Bharara is using his firing as “a political ploy.”

“One of the best ways he can make himself a hero to the political left, the people who would be supporting him, is to make him out to be a political martyr because he was supposedly ‘fired’ by the administration,” Mr. von Spakovsky said. “This is entirely a political ploy intended to enhance his political prospects.”

“Every political appointee in every administration knows that their jobs last as long as the president who appointed them wants them, or until the new president comes in,” he said. “That is the normal procedure.”

The White House said it is not “relevant” whether Mr. Trump told Mr. Bharara that he would keep his job during the new administration, as the prosecutor asserts.

“I don’t think it really matters at the end of the day,” Mr. Spicer told reporters. He said the president called Mr. Bharara last week to “thank him for his service.”

He said most U.S. attorneys from the Obama administration had already submitted their resignation letters. “This is just the final swathe of individuals who had not [resigned] at this time,” Mr. Spicer said.

Mr. Obama appointed Mr. Bharara to the post in 2009. His high-profile cases include investigations into Wall Street and opening political corruption probes involving the administrations of Gov. Andrew Cuomo and New York City Mayor Bill de Blasio — both Democrats.

Mr. Bharara could not be reached for comment Monday. On Sunday he wrote cryptically on Twitter, “By the way, now I know what the Moreland Commission must have felt like.”

Mr. Cuomo created the state’s Moreland Commission to Investigate Public Corruption in 2013 to probe elected officials and political organizations for violations of New York election and campaign laws. But he disbanded it less than a year later after approving minor reforms.

Mr. Bharara had said he would continue investigating the commission’s targets and the governor’s office.